Vermiculite

About: Vermiculite is a research topic. Over the lifetime, 2320 publications have been published within this topic receiving 37142 citations.

The chemical composition and structure of a 14 a intergradient mineral in a korean ultisol

Abstract: A B S T R A C T: An intergradient 14 A mineral showing X-ray diffraction features of "chloritized" vermiculite in a Korean Ultisol was studied. The structural formula of the whole 2 : 1 layer-silicate (14 A mineral and mica) in the Na+-saturated 0.24).5 /~m fraction was obtained by elemental, thermogravimetric and 29Si and 27AI nuclear magnetic resonance spectroscopic analyses in combination with extraction of the interlayer material from the 14 A mineral by hot 1/3 M sodium citrate treatment. This formula showed: (1) the 2 : 1 layer contains nearly one AI 3+ in four tetrahedral positions, and AI 3+ is the dominant cation in the octahedral sheet; (2) K +, exchangeable Na + and sodium citrate extractable 1 : 1 layer occupy the interlayer space of the 14 & mineral in similar proportions. Very little interlayer K was replaced by Na + during the citrate treatment. Possible schemes of alteration of the 2 : 1 layer to the 1 : 1 layer as its interlayer material are discussed. Many soils formed under leaching conditions in the humid temperate region contain a 14 intergradient mineral as a major clay component. It is called partially interlayered or "chloritized" vermiculite. "Chloritized" vermiculite is commonly identified by X-ray powder diffraction (XRD) analysis: it does not collapse readily when K-saturated, but its 14 ~ reflection becomes diffuse and shifts toward 10 ~ on heating to 300 ~ and 550~ (Rich, 1968; Barnhisel & Bertsch, 1989). When A1 is removed by treatment with reagents such as hot 1/3 M sodium citrate, the mineral collapses on K-saturation but does not expand with glycerol solvation. The following two observations on the 14 ~ mineral in several Korean Ultisols and Alfisols, however, questioned this identification: (1) the citrate treatment which resulted in removal of the interlayer material also resulted in dissolution not only of A1, but of Si at the molar Si/A1 ratio of -1-0; (2) the dissolution of the kaolin group mineral was indicated by difference infrared (IR) spectroscopy but not by XRD analysis for the citrate-treated and untreated samples. On the basis of these observations, Wada & Kakuto (1983a,b) suggested that the 14 & mineral is an intergradient vermiculite-kaol in mineral, in which each 14 & layer partially transforms into double kaolin layers. Later, ultramicrotomy and transmission electron microscopy (Wada & Kakuto, 1989) showed that the 14 ~ mineral particles are composed of stackings of more or less curved and often discontinuous silicate layers. On saturation with K +, the silicate layers had spacings of 14-10 ~, with 14-12 being dominant. There was, however, no indication of the double kaolin layers with a spacing of 7 & close to the edge of each 14 & layer as suggested earlier. In the present study, XRD, chemical, thermogravimetri c and 29Si and 27A1 nuclear

Composition and process for a granular plant nutrient

Abstract: Granular, free-flowing, slow release plant nutrient compositions suitable for use in growth media are prepared by treating granules of a calcined clay, such as montmorillonite, attapulgite, sepiolite chlorite or vermiculite, with one or more solutions of salts of iron, boron, molybdenum, chloride, manganese, zinc, copper and sulphur. Optionally, the salt solutions may contain a sequestering agent.

The structures of ornithine-vermiculite and 6-aminohexanoic acid-vermiculite

Abstract: Fourier syntheses have been used to establish the arrangement of organic molecules in the interlamellar regions of a 16.10 A phase of ornithine-vermiculite and a 16.92 A phase of 6-aminohexanoic acid-vermiculite. The organic cations form two layers parallel to the silicate surfaces in ornithine-vermiculite and in 6-aminohexanoic acid-vermiculite the organic cations form ascending and descending “stairs” from the silicate sheets.

Production of articles from minerals

Abstract: Vermiculite ore is contacted with an aqueous solution with at least one salt of sodium, lithium or an organosubstituted ammonium cation followed by aqueous washing so that the ore swells. The swollen vermiculite in aqueous suspension is subjected to a shearing action until a suspension containing vermiculite particles having dimensions less than 50 microns is produced with elimination from the suspension of all particles having a diameter larger than 50 microns. Water can then be removed from the suspension.

Evaluation of the tumorigenic potential of vermiculite by intrapleural injection in rats

Abstract: Hunter, B., and Thomson, C. (1973).British Journal of Industrial Medicine,30, 167-173. Evaluation of the tumorigenic potential of vermiculite by intrapleural injection in rats. Vermiculite, the geological name for a group of hydrated laminar minerals, has industrial application in areas previously restricted to the use of asbestos. In this assessment of its tumorigenicity, Rhodesian chrysotile asbestos or vermiculite was injected into the pleural cavity of rats. Mesotheliomata developed in 48% of the rats treated with asbestos. No tumours occurred which were associated with the vermiculite injections.